Photographic processing method utilizing electrophoresis and electrolysis of the developer

ABSTRACT

A method of developing photographic emulsion layers whereby fresh developer is supplied during development to different sized image areas in proportion to their size. Conventional development releases negatively charged waste particles that congregate adjacent the image areas. A positively charged electrode in the developer tank attracts the particles, permitting fresh developer to reach the image areas to continue development. Optionally, a negatively charged electrode electrolyzes the developer, releasing hydrogen bubbles which scrub the face of the developing layer; dislodging the waste particles.

United States Patent 7 2] Inventor Daniel J. Lasky Wappingers Falls,N.Y.

[21] Appl. No. 744,405

[22] Filed July 12, 1968 [45] Patented Oct. 26, 1971 73] AssigneeInternational Business Machines Corporation Armonk, N.Y.

[54] PHOTOGRAPHIC PROCESSING METHOD UTILIZING ELECTROPI-IORESIS ANDELECTROLYSIS OF THE DEVELOPER 8 Claims, 13 Drawing Figs.

[52] US. Cl 96/63, 96/48, 95/89, 204/180, 204/272, 204/299 [51] Int. ClG036 5/24 [50] Field of Search 96/48, 50, 63; 204/130, 180, 299

[5 6] References Cited UNITED STATES PATENTS 2,073,621 3/1937 Blaney96/63 X 2,356,536 8/1944 Rzymkowski 96/63 X 3,220,836 11/1965 Fairbank96/48 3,301,772 1/1967 Viro 96/48x OTHER REFERENCES Mason, PhotographicProcessing Chemistry," (New York, 1966) pp. 72, 73

Rzymkowski, Electrolytic Development of a Negative Film," Brit J. Phot.,84 p440 1937) Primary Examiner Norman G. Torchin Assistant Examiner-JohnWinkelman Attorneys-Hanifin and .lancin and A. Sidney Alpert ABSTRACT: Amethod of developing photographic emulsion layers whereby freshdeveloper is supplied during development to different sized image areasin proportion to their size. Conventional development releasesnegatively charged waste particles that congregate adjacent the imageareas. A positively charged electrode in the developer tank attracts theparticles, permitting fresh developer to reach the image areas tocontinue development. Optionally, a negatively charged electrodeelectrolyzes the developer, releasing hydrogen bubbles which scrub theface of the developing layer; dislodging the waste particles.

PATENTEDUET 2s IIIII 3.615.515

SHEET EDT 2 FIG. 7 APPLY VOLTAGE T0 ELECTRODES INTRODUCE LOAD AT 30 SECDRAIN INTRODUCE DEVELOPER PLATE IN mTERVALS DEVELOPER FIXER INTO TANKTANK FQRI5 5E0 INTO TANK T DRAW coIIIIIIIIous REIIovE RIIIsE T0 DRYERFIG.8 I

DEVELOP R v H613 A 184 FIXER IL I82 m I we RIIIsE ELECTRODE H6 VOLTAGETTTUTJTHTL 5 e 9 I2 I5 TIME (MIN) FIG.9

. I DRAIN DRAIN RIN E DR N A APPLY DEVELOPER; STOP, BATH;

IIIIIII INTRODUCE VOLTAGE mmooucg' mnwnuce WATER DEVELOPER ETC. STOPBATH HARDENER L DRAIN WATER; DRAIN BLEACH; DRAINEYWATER; DRAIN FIXER;INTRODUCE INTRODUCE INTRODUCE RINSE wmI BLEACH IIIAIER FIXER WATER FIG.H

FIGJZ PI-IOTOGRAPHIC PROCESSING METHOD UTILIZING ELECTROIIIORESIS ANDELECTROLYSIS OF THE DEVELOPER BACKGROUND OF THE INVENTION The presentinvention relates generally to the field of photographic processing, andmore particularly to improved apparatus and methods of developingexposed photographic emulsion layers which are carried, for example, onglass plates or film strips.

The role of photography in the microelectronics or printed circuitindustry has taken on new dimensions as the industry has expanded.Printed circuit technology is ever posing greater demands uponphotography, requiring, for example, photographic master patterns forproducing etched circuits having line width tolerances held topreviously unattainable limits. The tolerance problem is critical sinceinaccuracies of the master patterns are reflected by magnifiedinaccuracies on the circuit boards. The workers in the photographic artshave responded to these demands by building automatic processors thathave, in certain functions, virtually replaced manual photographicprocessing techniques. These automatic processors are good, but as yetare not good enough for high-quality, close tolerance worker, e.g.,where line widths on a master pattern plate or film strip must beuniformly held to one thousandth of an inch.

A brief summary of photographic processing will quickly point out someof the difficulties in close tolerance developing. The conventionalphotographic processing involves first subjecting an exposedphotographic element having an emulsion layer that contains, forexample, silver halide grains, to a developing bath and thereafter tofixing and washing baths. The mechanism of the most common developingreaction, i.e., the so-called chemical process, involves the reductionof silver ions to metallic silver by a suitable reducing solution ordeveloper. As developing occurs (which is, in fact, anoxidation-reduction mechanism), negatively charged waste particles arereleased into the developer, such as chloride, bromide, or iodizedsalts. These salts accumulate adjacent the exposed areas of the emulsionlayer and repress or inhibit development by preventing the access byadditional, fresh developer to the exposed areas. This condition isunacceptable as it leads to nonuniform development, and thus leads tononuniformity in-line width in the pattern developed on the photographicelement. The condition has been alleviated, in part, by the use ofvarious agitation arrangements that attempt to convey fresh developer tothe exposed areas of the emulsion layer.

It has been found that agitation of the developer during the developmentmechanism is necessary for a controlled process. In the prior art, theagitation arrangements have conventionally taken the form of either amechanical paddle wheel assembly that agitates the entire developerbath, or a nitrogen bubble system for localized agitation adjacent theexposed areas of the emulsion layer. These arrangements are well knownin the prior art, and are commonly regarded as the most controllable ofthe available agitation systems. However, even the best of these priorart arrangements does not differentiate between an area of the emulsionlayer that calls for .more fresh developer and an area that needs littleor no further development. This leads to nonuniformity in thedevelopment and, as noted above, ultimately results in variations ornonuniformity in line widths. Further, while the conventional agitationarrangements are intended to, and do displace a majority of the wasteparticles from their initial locations adjacent the exposed emulsionsurfaces, in many cases the waste particles are permitted to recirculatethrough the developer, causing a generalized exhaustion of thedeveloper. Further, the particles may fall to the floor of the developertank tending to clog the agitation system.

Accordingly, it is a general object of the present invention to provideapparatus and methods intended to overcome these above mentionedproblems in prior art photographic development processors.

It is a more specific object of the present invention to provideapparatus and methods that permit uniform development of exposed areasof a photographic emulsion layer and thereby produce essentially uniformpatterns having uniform line widths on photographic elements.

A further object of the present invention resides in the provision of aphotographic development process that utilizes electrophoresis andelectrolysis to obtain nonmechanical, and image dependent agitation of adeveloper bath.

Additional objects of the invention include, but are not limited to theprovision of apparatus and methods for photographic processing that:

1. permit single tank processing of photographic elements withoutnecessitating the removal of the elements prior to completion of thelast process step;

2. are equally compatible to black and white or color processing;

3. are relatively simple in operation and inexpensive to build andoperate; and

4. do not present a safety hazard to operating personnel.

SUMMARY OF THE INVENTION I provide, in one form of the invention, aprocessing tank in which an exposed photographic element is subjectedsuccessively to various treating baths or solutions. In this regard, acontroller operates fluid pumps to introduce, in timed succession, adeveloper, a fixer and a water bath into the tank containing the exposedphotographic elements.

The processing tank is arranged, in one embodiment, to receive a platehanger in which is mounted a photographic plate having an exposedemulsion layer. Mounted in the tank on the side of the plate adjacentits exposed emulsion layer is an electrode screen or grid that isconnected to a source of positive DC potential. Also mounted in thistank adjacent the lower end of the plate hanger, is a second electrodethat extends across the width of the plate hanger. This second electrodeis connected to a source of negative DC potential.

When the developing solution is introduced into the tank with an exposedplate therein, an oxidation-reduction reaction between the developer andexposed emulsion layer produces negatively charged particulate wasteproducts that congregate or collect in a location immediately adjacentthe exposed or image areas of the emulsion layer. This precludes freshdeveloper from approaching the exposed areas inhibiting development. Asexplained previously, this phenomena is familiar to those skilled in theart.

In the prior art, these waste particles are variously termed oxidationproducts or nonmetallic salts. In the exemplification, the particles areformed by reaction of hydroquinone with sulfite. Under influence of thecontroller, positive DC potential of a preselected magnitude is appliedto the electrode screen and negative DC potential of a preselectedmagnitude is applied to the second electrode. The second electrodeelectrolyzes the developer, releasing fine hydrogen bubbles that riseupwardly across the face of the emulsion layer. These bubbles causeagitation as they reach the waste particles, effectively breaking freeor dislodging the particles from their initial locations adjacent theexposed areas of the emulsion layer. Simultaneously, the positivelycharged electrode screen attracts the negatively charged wasteparticles, and the particles move toward the electrode screen permittingfresh developer to replace them adjacent the exposed emulsion areas. Inthis manner, additional fresh developer is directed preferentially tothe exposed emulsion areas to an extent proportionate to the rate ofremoval of waste products therefrom, providing, in effect, preferentialagitation of the developer at image sites to an extent proportionate tosite area size.

The advantages of the above described invention are many. In part, thearrangement is relatively simple, requiring no moving parts, externalmechanical drives or compressed nitrogen supplies as necessitated by theprior art agitation arrangements. Additionally, there is norecirculation of the waste particles within the developer, as theparticles are eventually collected on the electrode screen. Thisinhibits exhaustion, and increases the useful life of the developer. Theinvention achieves consistently developed patterns with precise, uniformline widths at a yield heretofore unavailable with known prior artagitation arrangements.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall view, partiallyin perspective and partially in schematic, illustrating one preferredform of the apparatus used in the practice of the present invention;

FIG. 2 is an enlarged partial vertical sectional view takensubstantially on the plane of line 2-2 in FIG. 1;

FIG. 3 is still further enlarged and partially schematic cross sectionof a portion of the apparatus illustrated in FIG. 2;

FIG. 4 is a front elevational view of a representative master plateproduced in accordance with the present invention;

FIG. 5 is an enlarged view of a portion of the face of the plate shownin FIG. 4, illustrating the uniformity in line width achieved by meansof the present invention;

FIG. 6 is a view similar to that of FIG. 5 showing the type of linevariations or nonuniformity occuring in plates developed by prior artapparatus;

FIG. 7 is a timing diagram that, taken in conjunction with FIG. 7,further explains the steps that take place in a preferred processcomprising an aspect of this invention;

FIG. 8 is a timing diagram that, taken in conjunction with FIG. 7,further explains the steps that take place in a preferred processcomprising an aspect of this invention;

FIG. 9 is another block diagram also showing a series of steps used topractice the present invention; and

FIGS. 10, ll, 12 and 13 illustrate in perspective and cross section asecond preferred form of the apparatus comprising an aspect of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now more specificallyto the drawings and particularly to FIGS. 1, 2 and 3, I have shown oneform of the apparatus used in the practice of my invention. Theapparatus includes an insulative processing tank generally denoted byreference numeral that is of generally rectangular shape. The tank 10 isadapted to receive a plate carrier shown in phantom line in FIG. 1 anddesignated by numeral 12. The carrier 12 comprises a frame 14 having anupwardly extending handle 16 that permits easy transport of the carrier.The carrier 12 has mounted therein a photographic plate 18 as shown inFIG. 2. In the exemplification, the plate is an Ortho Type III glassplate generally used in printed circuit fabrication to produce masterpatterns. The plate 18 has the usual emulsion layer 20 on one face, asshown in exaggerated fashion in FIG. 3 for purposes of illustration. Inpractice, the emulsion layer, which normally carries silver halidegrains, is exposed either manually or by a conventional automatic artwork generator such as the well known numerically controlled Gerber 500Artwork Generator." A representative plate is shown in FIG. 4 as having8 frames with preselected patterns. As will be noted, frame 22 hashorizontal lines and frame 24 has vertical lines. In actual practice,the pattern includes a plurality of parallel lines 26 that are 0.002inch wide with 0.002-inch spacing therebetween, and one or more0.125-inch lines 28. A pair of channels or grooves 46 and 48 foraccommodating the frame 14, permit the frame 14, carrying the plate 18to be readily mounted in and/or removed from the tank 10.

It is important that the lines 26 and 28 be extremely uniform in widththroughout their length and that the spaces therebetween be precise,e.g., 10.00l-inch tolerance. This is because the developed plates areused as master patterns in the production of printed circuit boards, asfor example, by well known photographic etching techniques. It is wellknown that variations in line widths on the master plate will generateeven greater variations in line widths on the finished printed circuitboard or element, which is intolerable as line width variations on theprinted circuit board result in variations in electrical parameters.

In order to provide an agitation system that will ultimately result inthe production of uniform lines on plate I8, in accordance with theinvention, there is mounted in the tank 10 a first electrode 30 bymounting means such as screws 32. The electrode 30 shown in theexemplification is, in the actual practice of the invention, a platinumplated titanium screen having a rather fine mesh. This type electrode isused as it has proved to be quite resistant to the acidic and basicsolutions introduced into the tank 10 during processing. However, it iscontemplated that other suitable electrode configurations could be used,for example platinum expanded plates or screens or the like. As will beseen in FIGS. 1-3, the electrode 30 is mounted in parallel relationshipto the major walls 34 and 36 of tank 10, and is closely adjacent wall36. In addition, it will be seen that the electrode 30 parallels plate18 when the plate is in place in tank 10. In the case of the actual tankthat I use to practice my invention, a spacing between the plate 18 andelectrode 30 of approximately one inch was used since the results werefound to be most satisfactory at this distance. However, it iscontemplated that the spacing between plate 18 and electrode 30 could bevaried between 1/16 and 1% inches, according to the materials used, etc.In actual practice,-the dimensions of the tank 10 are as follows; width,approximately 21.5 inches, depth, approximately 2.7 inches and heightapproximately 24.5 inches. A tank this size will accommodatephotographic plates up to 16 by 20 inches. The tank body must beconstructed of electrically insulated material, and l constructed thetank of Plexiglas," although other materials could obviously be used.

Also mounted in the tank 10, and generally adjacent the lower end of theplate 18 when it is in place in the tank I0, is a second electrode 40.Electrode 40 is spaced slightly away from the lower wall 42 of the tank,and extends somewhat past the emulsion layer 20 of plate 18. The secondelectrode 40 is mounted on tank wall 34, and as will be seen in FIGS. 2and 3 has a raised ridge 44 terminating in close proximity to the faceof emulsion layer 20. Of course, the electrode 40 extends approximatelythe full width of the tank 10 underlying plate I8. In actual practice,electrode 40 is a stainless steel plate having dimensions ofapproximately 1% by 20% by A: inches.

In the preferred embodiment, schematically shown in FIG. I, black andwhite photographic elements such as the plate 18 may be processed. Inthis regard, a developer or developing agent 50 is contained in aservice tank 52 and a fixer or fixing agent 54 is contained in anotherservice tank 56. A hose or conduit 58 connects tank 52 to a developerpump 60 and another hose or conduit 62 connects tank 56 to a fixer pump64. The pumps 60 and 64 are connected by conduits 66 and 68 respectivelyto a manifold 70 that opens into the interior of processing tank 10.Also connected to the manifold 70 is a conduit 72 that is connected to awater supply solenoid 74 which is in turn connected to a suitable watersupply (not illustrated As will be appreciated, the tanks 52, 56 and thewater supply are used to introduce the developer 50, the fixer 54 andwater into the tank 10.

Since it is desireable to obtain automated and consistent control of theabove apparatus, l have provided a controlling means or controllergenerally denoted by reference numeral 78. Controller 78 is connected byelectrical leads 80, 82, 83 and 84 to a DC power supply 86, to thedeveloper pump 60, to the solenoid 74 and to fixer pump 64 respectively.In practice, the controller 78 comprises a cylindrical drum that isrotated at a constant speed to activate microswitches. Arrangements ofthis type well known to those skilled in the art as Program Drums. Itwill be appreciated, however, that any suitable control means foroperating electrical devices such as the pumps 60 and 64 and thesolenoid 74 may be utilized for this purpose. The purpose, of course, isto operate the pumps 60 and 64 in timed sequence to introduce thedeveloper 50 and the fixer 54 into the tank l0 and to introduce waterinto the tank thereafter.

In order to drain the tank 10, I have provided three outlet hoses orconduits 88, and 92 communicating with the interior the tank 10 andleading to a manifold 94. The manifold 94 in turn is connected byconduit 96 to a suitable drain pump 98 that is also operated by thecontroller 78, connected thereto by electrical lead 100.

Having now described the physical characteristics of the apparatus shownin FIGS. 1, 2 and 3, I will describe the operation of and mechanismsassociated with my invention. As known to those skilled in the art, whenan exposed photographic element is placed in a developer, the exposed orimage areas of the emulsion, that contain exposed silver halide grains,are converted to metallic silver by a reduction-oxidation mechanism. Thedeveloper is oxidized, and, as development commences, there is anaccumulation of salts in solution. In the exemplification, since I usein one application a hydroquinone developer such as Kodalith, adeveloper sold by the Eastman Kodak Company under that name, the saltthat is freed is a reaction product of hydroquinone with sulfite. As Ihave shown in FIG. 3, this reaction product takes the form of smallnegatively charged particles generally designated by reference numeral104. The particles 104 accumulate adjacent exposed or image areas 106and 108 of the emulsion layer 20 in proportion to the size (or width) ofthe image area. I have found that if these particles are permitted toremain adjacent the image areas of the emulsion layer 20, they impededevelopment.

In order to permit uniform development of the image areas 106 and 108, Iprovide the electrodes 30 and 40. The electrode 30 is connected byelectrical lead 110 to a positive source of DC potential in power supply86, and the electrode 40 is connected by lead 112 to a negative sourceof DC potential in the power supply. The electrode 40, when energized,electrolyzes the developer to produce or generate hydrogen bubbles 120.The bubbles occur uniformly across the width of electrode 40 flowingupwardly from the edge of ridge 44 in a plane closely adjacent the faceof plate 18 that carries the emulsion layer 20. The gaseous hydrogenbubbles are fine (approximately one twenty-fifth the size of bubblesgenerated by nitrogen bubblers) and evenly and closely spaced, andthereby avoid the major objection to nitrogen-bubblers; i.e., largebubbles that are too widely spaced apart. In operation, when thenegatively charged waste particles 104 begin to accumulate adjacenttheir exposed image areas 106 and 108, the electrodes 30 and 40 areenergized. Bubbles I20 thereby scrub the emulsion face, breaking looseor dislodging the particles I04. Simultaneously, electrode 40 attractsthe particles 104, drawing them away from their initial locationadjacent the image areas. This permits additional, fresh developer todisplace the particles adjacent the image areas, thereby permittingdevelopment to continue. The agitation resulting from this combinationof electrolytic action accomplished by electrode 40 and electrophoreticaction accomplished by electrode 30 is responsive to the number ofparticles generated, and thus may be termed Image Dependent Agitation."In this regard, the amount of fresh developer that can approach theimage areas is dependent upon the number of waste particles 104 drawnaway for their initial location.

It may now be asked why I have taken such pains to move the wasteparticles 104 away from the photographic plate 18 and why it isimportant for this to be accomplished in an image dependent manner. Ihave shown a representative type of photographic plate with a masterpattern thereon in FIG. 4, and what two of the 2 mil (0.002 inch) lineslook like when the plate has been developed using the apparatus of thisinvention (FIG, 5) and by the prior art apparatus (FIG. 6). Aspreviously mentioned, the representative pattern has a plurality of 2mil horizontal and vertical lines and one or more 125 mil lines. Themajority of the developed 2 mil lines appear as shown in FIG. 6 whenconventional apparatus is used to agitate the developer. That is, thelines and the spacings therebetween are irregular and nonuniform. Thisis because the prior art apparatus is incapable of differentiatingbetween an image area that calls for more fresh developer and an imagearea that needs little or no development. It will be understood thatmore developer is needed adjacent the 125 mil lines than is neededadjacent the 2 mil lines, and that the prior art apparatus is notresponsive to this difference. What actually happens using the prior artpaddle wheel is that sufficient stirring of the entire developer bath tosupply the large image areas 106 with an adequate supply of freshdeveloper will cause the smaller image area 108 to be overdeveloped, andvice versa. In the prior art nitrogen bubble systems, the large, spreadapart bubbles displace the waste particles irregularly across the imageareas on the plate, leading to variations in development. This leads tothe type of developed line as shown in FIG. 6, where portions 107 of theline between bubbles are underdeveloped and hence neck down, while otherportions are overdeveloped and hence are too wide.

On the other hand, the uniformity of development, and hence line widththat I am able to achieve by the use of the present invention is shownin FIG. 5. Not only is the developed line 16 of FIG. 5 uniform, but I amable to achieve uniformity of spacing between lines and even developmentof both wide (235 mil) narrow (2 mil) lines. I have thus been able tosurpass the tolerance requirements for the master plates, as well asbeing able to achieve remarkable consistency between plates.

Referring now to FIGS. 7 and 8, l have shown the steps and a timingdiagram of the process as practiced in one preferred fashion using theapparatus of FIG. 1. Under the operation of controller 78, a developer(e.g. Kodalith) is initially introduced into the tank 10 by developerpump 60. The plate carrier 12 carrying an exposed plate 18 is loadedinto the tank 10 by sliding it into channels 46 and 48. The negativelycharged waste particles 104 immediately begin to collect or congregateadjacent image areas such as 106 and 108 as the oxidation-reductionmechanism of development occurs. Without some agitation, the particles104 will remain suspended adjacent the image areas until they graduallysink to the bottom of tank 10. Accordingly, while the developer is inthe tank, i.e. for approximately three minutes as required for Kodalithdeveloper, approximately 6 volts DC is applied to electrodes 30 and 40at 30 second intervals for 15 second durations. This permits uniformdevelopment to occur. After the 3 minute development and agitationperiod, the controller 78 energizes pump 98 to drain the developer fromthe tank, with drainage taking approximately 15 seconds. When the tankis drained, the controller 78 turns pump 98 off and turns pump 64 on,filling the tank 10 with a suitable fixer 54. The fixer 54 is permittedto remain in the tank for three minutes, after which controller 78 againactuates pump 98 to drain the fixer from tank 10. When the tank isdrained, controller 78 actuates water supply solenoid 74, permittingfresh water to continuously enter the tank 10 and flow over the tank topfor 7 minutes. At this time, controller 78 turns solenoid 74 off andagain activates pump 98 to drain the tank of water. This concludes theprocessing of plate 18, and the carrier 12 is removed from tank 10. Theplate 18 will normally then be taken to a dryer.

As will be understood by the previous description of the process, thedeveloping, fixing, and wash cycling takes place in the single tank 10.This is quite advantageous since it minimizes processing errors, andalso minimizes safety hazards since the glass plate is not handledduring processing. In addition, this eliminates the requirements forseveral processing tanks, thereby conserving space in the dark room, andthe controller 78 insures that the time cycles are extremely accurate.

While I have described the invention in conjunction with FIGS. 1-3, Ihave actually reduced to practice a second embodiment of the inventionwherein I used only electrophoretic action to agitate the developer;i.e., using only the electrode 30 for drawing waste particles 104 awayfrom the image areas. I was able to accomplish this by applyingapproximately 26 volts positive DC potential to electrode 30 while alsoproviding a ground within the tank. In this regard, I used a groundconnection to a plate frame similar to frame 14, except that it wasconductive. I was, in this manner, able to effectively develop the imageareas of the exposed photographic element with accuracy of line width asin the first embodiment described above. The remaining steps of thisprocess are the same, with the only difference in this second embodimentbeing the absence of electrode 40 and a higher voltage being applied toelectrode 30 to overcome the inertia of particles 104 and draw themtoward electrode 30.

It will occur to those skilled in the art that the present invention, asexplained so far, has related to black and white film processing,whereas the invention is also equally applicable to both color andreversal processing. Accordingly, in FIG. 9 I have shown one of severalprocesses that I have performed in a single tank similar to tank 10,having electrodes such as electrodes 30 and 40. Of course, it isnecessary to add additional service tanks to contain a stop bath, ahardner, and a bleach, and to include pumps therefor. This also requiresthat the program in controller 78 be changed to control such additionalpumps as are needed to practice a color or a reversal process.Therefore, as should be understood, in the process shown in FIG. 9,electrophoretic and electrolitic agitation take place during developing,and all the process steps take place in a single tank.

Referring now specifically to FIG. 9, I have shown a precess fordeveloping Ektacolor film, using the well known Kodak C- 22 developerand a conventional stop bath, hardener, bleach and fixer all of whichare usually specified for use with Ektacolor photographic elements.Initially, a photographic plate is loaded into a tank such as tank 10and washed with water. The water is thereafter drained, and thedeveloper introduced into the tank. As explained above, negativelycharged waste particle immediately begin to collect adjacent the imageareas, and therefore voltage is applied to the two electrodes in thetank at 30 second intervals for second duration while the developer isin the tank. The developer is then drained and stop bath is introducedinto the tank under influence of a controller. After a preselectedperiod, the stop bath is drained and the hardener introduced into thetank, the hardener drained and water again introduced into the tank. Thewater is then drained, a bleach introduced, the bleach drained and wateragain introduced. After the water is again drained a fixer is introducedinto the tank, the fixer drained and the plate is rinsed continuouslywith the water flowing over the top as explained above. This process hasall the advantages mentioned above in conjunction with black and whiteprocessing, and additionally has the advantage of replacing several ormore separate operations as all the processing steps take place in asingle tank.

The previous embodiments of the invention have been explained inconjunction with a generally rectangular tank that accommodates glassplate type photographic elements. I can, by the present invention, alsoautomatically process sheet film using electrophoretic and electrolyticaction as explained above. Accordingly, I have shown another embodimentof the invention in FIGS. 10-13 for accomplishing sheet or strip filmprocessing. The apparatus shown in FIGS. 10-13 achieves essentially thesame benefits as that illustrated in the above described embodiments.While the type of photographic element to be handled by this apparatusdiffers, electrophoretic and electrolytic agitation is still applied.The developing apparatus, generally designated by reference numeral 150comprises a processing tank 152 that, as will be seen in FIG. 11, is ofa cylindrical shape. The tank 152 has a center mounting post or spindle154 that is adapted to receive the hub 156 of a film carrier spool 158.The tank 152 has an enlarged hollow base 160. As is the case with tank10, the tank 150 and its base 160 are composed of electricallyinsulative material, such as the well-known Plexiglas." Connected to thebase 160, and communicating with the interior of base 160 and tank 150are four conduits or hoses 162, 164, 166 and 168. These conduits performa similar function as the conduits 66, 68, 72 and 96 as shown above andexplained in conjunction with FIG. 1. Thus, for example, conduit 162 maybe connected to a developer tank, conduit 164 may be connected to afixer tank, conduit 166 may be connected to a water supply and conduit168 may be connected to a pump and drain. 0n the floor of the base is anelectrically conductive annular plate seated around the post 154. Plate170, in the exemplification, is a stainless steel plate, and as shownschematically, is connected by lead 172 to the negative side of a DCpower supply (not illustrated).

The spool 158 has two end flanges 174 and 176, connected by hub 156 thathas an opening 157 extending therethrough. The flange 174 and the hub156 are constructed of a suitable insulative material such a Plexiglas."A carrying handle is connected to flange 176 to facilitate carrying thespool 158. The end flange 176 is shown both in FIGS. 10 and 12. Thisflange 176 is constructed of an electrically conductive material,preferably stainless steel, and has a pair of spiral grooves 182 and 184in its inner face 186 that wind inwardly to hub 156 (see FIGS. 12 and13). Mounted in the spiral groove 184 is an electrode 188 similar toelectrode 30 described above, that in the exemplification takes the formof a platinum-plated titanium screen. The bottom of groove 184 isinsulated at 187,

so as to electrically insulate the electrode screen 188 from thestainless steel flange 176. The electrode screen is coiled or spiral inshape, following the spiral groove 184 as shown in particular in FIG.12. Connecting means (not illustrated, but that may be in the form of asimple clip-on connector) is provided for connecting the electrodescreen 188 to the positive side of a DC source in a similar fashion asexplained above.

In order to load a film strip in the spool for processing of the exposedor image areas thereon, it is merely necessary to thread the film intothe spiral groove 182 until it reaches the inner end of the grooveadjacent hub 156. To facilitate this threading another mating groove maybe provided in the inner face of flange 174. The film strip is shownschematically in FIG. 10 at 159. It will be appreciated that whenthreaded into spool 158, the film strip 159 will be in close proximityto the electrode screen 188 throughout its length, and of course, thefilm will be arranged so that its emulsion surface is adjacent theelectrode screen 188. When the film is in place in spool 158, the spoolis slipped onto post 154 into the tank 152. The flange 176 acts ineffect as the second electrode, as it makes electrical contact withplate 170 which is connected to a negative DC source. The developer isintroduced into the tank, for example, through conduit 162 under theinfluence of a suitable controlling means. Since negatively chargedwaste particles form, positive potential is applied to electrode 188 andnegative potential is applied to plate 170 and thus to flange 176 toagitate the developer. The negatively charged flange 176 electrolyzesthe developer, causing gaseous hydrogen bubbles to flow upwardly acrossthe emulsion surface of film strip 159. This dislodges the particulatewaste particles from their initial locations adjacent the exposed orimage areas of the film. At the same time, the positively chargedelectrode screen 188 attracts the particles, drawing them away fromtheir initial locations permitting additional, fresh developer access tothe image areas. The remainder of the process is essentially the same asthat described above in conjunction with FIGS. 7 and 8.

This embodiment of the invention as shown and described in conjunctionwith FIGS. 10-13 offers the same advantages as mentioned above. Itpermits a film strip to be processed under the influence ofelectrophoretic and electrolytic agitation. Further, film strips of thelengths I am able to process in wound form in spool 158 e.g. 5 feet inlength and 36 to 40 inches in width) previously necessitated large traysand process sinks covering a length of approximately 15 feet ofprocessing area. By the present invention however, the tank 152 needmerely be approximately 8 inches in diameter. It will be apparent tothose skilled in the art that color film may be processed by tank 152 ina manner as explained in conjunction with FIG. 9 above.

While I have explained my invention in conjunction with the embodimentsshown in the drawings, it will be appreciated that the apparatus couldtake other forms while still incorporating the essence of the invention.It will occur to those skilled in the art that not only can I processblack and white film and plates, but that other film types such asAnscochrome, Super Anscochrome, Ektachrome, etc., can be processed bythis invention. Further, while I have shown in the preferred embodimentsof the invention desired dimensions of the tanks and desired magnitudesof voltages applied to the electrodes, these dimensions and magnitudesare dependent upon the photographic element being developed and the typeof developer being used. Therefore, it will be understood that I canvary the tank size, as the photographic elements and developers arevaried, and that the tank may be enlarged to accommodate multiplephotographic plates. It will also be understood that other varioussubstitutions or changes in form and details of the devices and in theiroperation may be made by those skilled in the art without departing fromthe true spirit and scope of the invention. It is accordingly desiredthat theappended claims shall not be limited to the specific details ofthe invention.

lclaim:

1. In a process for obtaining substantially uniform development ofvariably dimensioned photoexposed image areas of photographic elementsby immersion of the elements in a developer solution container in aprocess tank, whereby electrically attractable development reactionproducts are formed at image sites in said image areas and tend toaccumulate in suspension in the solution adjacent to respective sites,the improvement comprising:

drawing the suspended products away from said sites during saiddevelopment by applying thereto an electrical field of a predeterminedmagnitude which attracts the suspended products away from said sites andthereby admits fresh developer solution to circulate to said sites withthe circulation of said fresh developer relative to image areas ofdifferent size generally varying in proportion to respective area size.

2. The process of claim 1 including the step coincident with andsupplementing said drawing step of providing a uniform gentle agitationof said developer solution generally parallel to and covering allelement surfaces containing said image areas, in order to gently movesaid suspended products from respective suspension sites, byelectrolyzing the developer solution in the tank at a level below theelement, thereby releasing a uniform stream of fine bubbles adjacent andparallel to all developing surfaces of the element.

3. The process of claim 2 wherein said electrical field is establishedby applying positive electrical voltage to an electrode located in theprocess tank facing and parallel to the developing surface of saidelement, and the coincident step of providing said agitation is effectedby applying negative voltage to an electrode positioned below thedeveloping surface and having a geometric shape conforming to an edge ofthe surface thereby electrolyzing the developer solution to produce finebubbles rising in a uniform formation generally parallel and proximatethe surface.

4. The process of claim 2 wherein said process tank is insulatedrelative to said element and electrical field.

5. A method of processing high resolution gelatino silver halidemicrophotographic elements, each element having an exposed highresolution gelatino silver halide emulsion layer, by

immersion of said elements in an aqueous developer contained in aprocessing tank whereby electrically attractable development reactionproducts are produced in suspension comprising:

locating a first electrode in the tank below a bottom edge of theelement and a second electrode in the tank generally parallel to andfacing the emulsion side of the element; simultaneously applyingnegative direct current potential to the first electrode and positivedirect current potential to the second electrode during the processingof said element thereby variably agitating the developer in the imageareas of the emulsion surface in proportion to respective area sizes;and, with said electrodes deactivated:

. draining the developer from the processing tank; and introducing 1ntimed sequence into the processing tank at least a fixer and water tocomplete the processing of the photographic element in sim in theprocessing tank.

6. The method of claim 5 wherein the step of simultaneously applyingsaid negative direct current potential to said first electrode andpositive direct current potential to said second electrode includesapplying the potentials at approximately 30 second intervals duringdevelopment for a duration of approximately 15 seconds for eachapplication.

7. In a photographic image development process involving immersion of anexposed high resolution gelatino silver halide photographic emulsionlayer in an aqueous developer fluid medium contained in a process tankand characterized by reaction of said emulsion layer with said medium toform visibly contrasting image and nonimage areas therein andcharacterized further by formation of particulate development reactionproducts exclusively in said image areas and accumulation of saidproducts in suspension adjacent said image areas, the improvement stepsof:

subjecting said immersed emulsion layer while it is undergoingdevelopment to a uniform electric field spanning said image and nonimageareas, and having polarity and intensity sufficient to attract suspendedreaction product particles away from said image areas; and

collecting said attracted reaction product particles at a charged screenelectrode located in said tank.

8. in a photographic image development process involving immersion of anelement which contains an exposed high resolution gelatino silver halidephotographic emulsion layer in an aqueous developer fluid contained in aprocess tank the improvement steps of:

generating a highly uniform stream of fine hydrogen bubbles during saiddevelopment process by electrolyzing said fluid within said tank at alevel below said immersed layer; and

positioning said element in said tank to receive said bubbles in auniform flow formation proximate andparallel to the entire developingsurface of said emulsion layer thereby gently inducing displacement ofdevelopment reaction products suspended in the fluid adjacent developingimage areas in the emulsion layer and permitting fresh developer fluidto contact said image areas.

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2. The process of claim 1 including the step coincident with andsupplementing said drawing step of providing a uniform gentle agitationof said developer solution generally parallel to and covering allelement surfaces containing said image areas, in order to gently movesaid suspended products from respective suspension sites, byelectrolyzing the developer solution in the tank at a level below theelement, thereby releasing a uniform stream of fine bubbles adjacent andparallel to all developing surfaces of the element.
 3. The process ofclaim 2 wherein said electrical field is established by applyingpositive electrical voltage to an electrode located in the process tankfacing and parallel to the developing surface of said element, and thecoincident step of providing said agitation is effected by applyingnegative voltage to an electrode positioned below the developing surfaceand having a geometric shape conforming to an edge of the surfacethereby electrolyzing the developer solution to produce fine bubblesrising in a uniform formation generally parallel and proximate thesurface.
 4. The process of claim 2 wherein said process tank isinsulated relative to said element and electrical field.
 5. A method ofprocessing high resolution gelatino silver halide microphotographicelements, each element having an exposed high resolution gelatino silverhalide emulsion layer, by immersion of said elements in an aqueousdeveloper contained in a processing tank whereby electricallyattractable development reaction products are produced in suspensioncomprising: locating a first electrode in the tank below a bottom edgeof the element and a second electrode in the tank generally parallel toand facing the emulsion side of the element; simultaneously applyingnegative direct current potential to the first electrode and positivedirect current potential to the second electrode during the processingof said element thereby variably agitating the devEloper in the imageareas of the emulsion surface in proportion to respective area sizes;and, with said electrodes deactivated: draining the developer from theprocessing tank; and introducing in timed sequence into the processingtank at least a fixer and water to complete the processing of thephotographic element in situ in the processing tank.
 6. The method ofclaim 5 wherein the step of simultaneously applying said negative directcurrent potential to said first electrode and positive direct currentpotential to said second electrode includes applying the potentials atapproximately 30 second intervals during development for a duration ofapproximately 15 seconds for each application.
 7. In a photographicimage development process involving immersion of an exposed highresolution gelatino silver halide photographic emulsion layer in anaqueous developer fluid medium contained in a process tank andcharacterized by reaction of said emulsion layer with said medium toform visibly contrasting image and nonimage areas therein andcharacterized further by formation of particulate development reactionproducts exclusively in said image areas and accumulation of saidproducts in suspension adjacent said image areas, the improvement stepsof: subjecting said immersed emulsion layer while it is undergoingdevelopment to a uniform electric field spanning said image and nonimageareas, and having polarity and intensity sufficient to attract suspendedreaction product particles away from said image areas; and collectingsaid attracted reaction product particles at a charged screen electrodelocated in said tank.
 8. In a photographic image development processinvolving immersion of an element which contains an exposed highresolution gelatino silver halide photographic emulsion layer in anaqueous developer fluid contained in a process tank the improvementsteps of: generating a highly uniform stream of fine hydrogen bubblesduring said development process by electrolyzing said fluid within saidtank at a level below said immersed layer; and positioning said elementin said tank to receive said bubbles in a uniform flow formationproximate and parallel to the entire developing surface of said emulsionlayer thereby gently inducing displacement of development reactionproducts suspended in the fluid adjacent developing image areas in theemulsion layer and permitting fresh developer fluid to contact saidimage areas.